This application relates to the subject matter of earlier application Ser. No. 07-022,512 filed 03-09-87 which was a continuing application of application Ser. No. 06-792,213 filed 10-28-85, both now abandoned.
The present invention relates to vehicle braking systems and in particular to vehicle braking systems having associated therewith an air flow for removing heat from the braking system.
There are a host of different braking arrangements for vehicles which have been proposed, with the most popular braking system being either the Drum Brake or more recently the Disk Brake. In addition to these two types of braking systems there is also what is referred to as a Ring Brake as generally shown in the U.S. Pat. No. 3,170,542 where braking can occur on both sides of the ring brake member.
Common to all of these braking systems is the dissipation of energy by means of heat which is generated at or on the braking surface. This heat is dissipated to the surrounding air environment by means of convection, however, due to the placement of the brake generally in a confined region under a vehicle, the circulation of air is relatively poor and the convection coefficient of heat transfer is relatively low. This problem of heat build-up is particularly acute where the brake must be operated frequently over a long period of time and thus the braking system does not have an opportunity to dissipate the heat when the brake is not in use. Such circumstances commonly occur with truck braking systems, particularly in mountains regions, and the possibility of brake failure is quite acute. For example, there are often run-off regions where vehicles that are out of control (i.e. where braking system is substantially lost) may exit into these regions which are designed to stop the vehicle.
Most conventional car braking systems operate satisfactorily, however, braking systems used to maximum, say eight times in a row, result in the effective braking power to be less than 50%. The principle reason for the reduction in braking power is heat build-up within the braking system.
Another problem associated with vehicle braking systems is in the transmission of the heat generated in the braking system to the wheel bearing of the vehicle. Wheel bearings have generally been protected from transfer of heat from the braking system, as the life of the wheel bearing would be substantially reduced if exposed to the heat generated in the braking system. Therefore, the prior practice has been to isolate the wheel bearing from a direct heat transfer path of the braking surface to the wheel bearing.
There remains a need for a simple effective braking system where heat can be efficiently removed from the braking surface to improve both the life and performance of the braking system.